Ethylene-α-olefin-nonconjugated polyene random copolymers such as EPDM, in general, are excellent in weatherability, heat resistance, and ozone resistance, and are widely used to make automotive industrial parts, industrial rubber products, electrical insulating material, civil engineering and construction material, rubberized fabric, etc.
Conventional ethylene-α-olefin-nonconjugated polyene random copolymer rubbers have the drawback of poorer compression set properties, as compared with silicone rubbers and the like. In order to solve the drawback, a method of adopting peroxide crosslinking in place of sulfur vulcanization is effective. This method, however, is disadvantageous in that in the case where hot air crosslinking by use of HAV (hot air vulcanization) or UHF (ultrahigh frequency electromagnetic waves) is performed, the rubber surface would not be crosslinked or be deteriorated, leading to extremely poor scratch resistance.
Meanwhile, JP-A 4-185687 (Patent Document 1) discloses a composition which contains a compound having at least one alkenyl group in the molecule thereof, a compound having at least two hydrosilyl groups in the molecule thereof, and a hydrosilylating catalyst. This composition, however, is insufficient in curability, and its compression set property is also unsatisfactory.
JP-A 2001-31802 (Patent Document 2) discloses a composition which contains an alkenyl group-containing compound having a specific structure, a compound having at least two hydrosilyl groups in the molecule thereof, and a hydrosilylating catalyst. However, the SiH compound used in Examples has a demerit in that the rubber compound after mixing has a very short pot life at room temperature, so that the workability (handleability) and shelf stability are poor. Therefore, the composition is unsuitable for ordinary rubber forming processes.
JP-A 2001-279027 (Patent Document 3) discloses an alkenyl group-containing compound having a specific structure and a cyclic polysiloxane having at least two SiH groups in one molecule thereof. However, the SiH compound used in Examples is only a polysiloxane having four SiH groups in one molecule thereof, and the composition is unsatisfactory in rubber properties.
JP-A 2008-156574 (Patent Document 4) discloses a method in which an alkenyl group-containing compound having a specific structure and a compound having two SiH groups and three SiH groups at terminal ends of the molecule thereof are used in combination. This material, however, is disadvantageous in that it is difficult to regulate the pot life at room temperature, the workability (handleability) and shelf stability are poor, and the material is unsuited to various forming or molding processes.